An Interface ASIC Design of MEMS Gyroscope with Analog Closed Loop Driving

Area of Science:

• Electrical Engineering
• Mechanical Engineering
• Sensor Technology

Background:

• Micro-electromechanical systems (MEMS) vibratory gyroscopes require sophisticated interface circuits for accurate angular velocity sensing.
• Traditional designs often face challenges with robustness and precise temperature compensation.

Purpose of the Study:

• To introduce a digital interface application-specific integrated circuit (ASIC) for MEMS vibratory gyroscopes.
• To enhance system robustness and achieve precise angular velocity measurement with integrated temperature compensation.

Main Methods:

• Developed an interface ASIC using an automatic gain circuit (AGC) for self-excited vibration, replacing phase-locked loops.
• Modeled the MEMS gyroscope's mechanically sensitive structure using Verilog-A for co-simulation.
• Created a system-level simulation model in SIMULINK, integrating mechanical and electrical components.
• Designed a sigma-delta (ΣΔ) analog-to-digital converter (ADC) for digital processing and temperature compensation using on-chip diode characteristics.

Main Results:

• Achieved a high signal-to-noise ratio (SNR) of 111.56 dB for the ΣΔ ADC.
• Demonstrated excellent system nonlinearity of 0.03% over the full-scale range.
• The AGC module provided good system robustness.

Conclusions:

• The developed digital interface ASIC significantly improves the performance and robustness of MEMS vibratory gyroscopes.
• Integrated on-chip temperature sensing and compensation effectively correct zero bias and enhance accuracy.
• The design, implemented in a 0.18 μm CMOS BCD process, meets stringent performance requirements for angular velocity sensing.